I keep tabs on my aunt all the time, cautioning her about the latest scams going around. She knows that, if she receives any sort of suspicious contact and is unsure what to do, she should call me. We youngsters don't necessarily have to take complete control of our older relatives’ finances, but we should take a special interest in our older family members, inform them about scams and tell them what to do if they receive any suspicious contact. They should also know they can come to us if they aren't sure what to do.
An elderly relative who lives alone got a similar call from the "IRS" saying she faced arrest unless she forked over her bank information.
Even though she handled the caller properly you could tell the episode shook her up.